bzr crashed when attempting to merge a Bazaar merge directive format 2 without target_branch

[David Coles]

Binary package hint: bzr

When attempting to merge a merge-directive, Bazaar crashes with "TypeError: __init__() takes at least 6 non-keyword arguments (5 given)". This appears to be caused by the merge directive missing a target_branch which is expected by the MergeDirective2 class.

# Bazaar merge directive format 2 (Bazaar 0.90)
# revision_id: <email address hidden>
# testament_sha1: f6ec130f0a3b31bcb1368160afb40632cf953863
# timestamp: 2010-11-10 12:35:36 +1100
# base_revision_id: <email address hidden>-\
# mf2vov0kvwdrf5n5
#
# Begin patch

I'm unsure if this is a bug in my version of Bazaar (for crashing when not explicitly given a target_branch) or the other user's version of Bazaar (for not adding a target_branch to the merge request).

ProblemType: Crash
DistroRelease: Ubuntu 10.10
Package: bzr 2.2.1-0ubuntu1
ProcCmdline: /usr/bin/python /usr/bin/bzr merge /tmp/highlight-20.patch

Traceback (most recent call last):
  File "/usr/lib/python2.6/dist-packages/bzrlib/commands.py", line 912, in exception_to_return_code
    return the_callable(*args, **kwargs)
  File "/usr/lib/python2.6/dist-packages/bzrlib/commands.py", line 1112, in run_bzr
    ret = run(*run_argv)
  File "/usr/lib/python2.6/dist-packages/bzrlib/commands.py", line 690, in run_argv_aliases
    return self.run(**all_cmd_args)
  File "/usr/lib/python2.6/dist-packages/bzrlib/commands.py", line 705, in run
    return self._operation.run_simple(*args, **kwargs)
  File "/usr/lib/python2.6/dist-packages/bzrlib/cleanup.py", line 135, in run_simple
    self.cleanups, self.func, *args, **kwargs)
  File "/usr/lib/python2.6/dist-packages/bzrlib/cleanup.py", line 165, in _do_with_cleanups
    result = func(*args, **kwargs)
  File "/usr/lib/python2.6/dist-packages/bzrlib/builtins.py", line 3831, in run
    possible_transports=possible_transports)
  File "/usr/lib/python2.6/dist-packages/bzrlib/bundle/__init__.py", line 52, in read_mergeable_from_url
    _do_directive)
  File "/usr/lib/python2.6/dist-packages/bzrlib/bundle/__init__.py", line 89, in read_mergeable_from_transport
    return MergeDirective.from_lines(bytef), transport
  File "/usr/lib/python2.6/dist-packages/bzrlib/merge_directive.py", line 416, in from_lines
    line_iter)
  File "/usr/lib/python2.6/dist-packages/bzrlib/merge_directive.py", line 540, in _from_lines
    **kwargs)
TypeError: __init__() takes at least 6 non-keyword arguments (5 given)

[Andrew Bennetts (spiv)]

Giving a traceback is certainly a bug. I'm not sure off the top of my head if no target_branch makes the merge directive invalid or not.

[David Coles (dcoles)]

The closest thing I can find is http://doc.bazaar.canonical.com/bzr.2.0rc2-html/developers/bundles.html which defers to Format 1 merge directives for explaining target_branch. From looking at the merge directives I've encountered it doesn't appear to be all that important - Bazaar will happily chug along with any old path, even if it's non-existent (so long as something is set).

[Matt Giuca (mgiuca)]

Note: The merge directive without the target_branch was not generated by Bzr ... it's my merge directive.

I noticed that the target_branch was a relative path to a directory on my machine which would make no sense to you. Since Bzr obviously ignores it anyway (because it just applies it to the current branch), I thought it would be safe to delete it, so I manually deleted that line before sending it to David. Turns out I was wrong.

I don't see how Bzr can make use of the target_branch (at least in this case), since the target branch was a local path on my machine. Since it clearly works without any sensible target_branch (since David was later able to apply the patch with the target_branch intact, even though that path did not exist on his machine), then I don't see why it is illegal to have a merge directive without a target branch.